Traumatic brain injury in elderly population: A global systematic review and meta-analysis of in-hospital mortality and risk factors among 2.22 million individuals

Background: Traumatic brain injury (TBI) among elderly individuals poses a significant global health concern due to the increasing ageing population. Methods: We searched PubMed, Cochrane Library, and Embase from database inception to Feb 1, 2024. Studies performed in inpatient settings reporting in-hospital mortality of elderly people ( >= 60 years) with TBI and/or identifying risk factors predictive of such outcomes, were included. Data were extracted from published reports, in-hospital mortality as our main outcome was synthesized in the form of rates, and risk factors predicting inhospital mortality was synthesized in the form of odds ratios. Subgroup analyses, meta-regression and doseresponse meta-analysis were used in our analyses. Findings: We included 105 studies covering 2217,964 patients from 30 countries/regions. The overall in-hospital mortality of elderly patients with TBI was 16 % (95 % CI 15 %-17 %) from 70 studies. In-hospital mortality was 5 % (95 % CI, 3 %-7 %), 18 % (95 % CI, 12 %-24 %), 65 % (95 % CI, 59 %-70 %) for mild, moderate and severe subgroups from 10, 7, and 23 studies, respectively. A decrease in in-hospital mortality over years was observed in overall (1981-2022) and in severe (1986-2022) elderly patients with TBI. Older age 1.69 (95 % CI, 1.58-1.82, P < 0.001), male gender 1.34 (95 % CI, 1.25-1.42, P < 0.001), clinical conditions including traffic-related cause of injury 1.22 (95 % CI, 1.02-1.45, P = 0.029), GCS moderate (GCS 9-12 compared to GCS 13-15) 4.33 (95 % CI, 3.13-5.99, P < 0.001), GCS severe (GCS 3-8 compared to GCS 13-15) 23.09 (95 % CI, 13.80-38.63, P < 0.001), abnormal pupillary light reflex 3.22 (95 % CI, 2.09-4.96, P < 0.001), hypotension after injury 2.88 (95 % CI, 1.06-7.81, P = 0.038), polytrauma 2.31 (95 % CI, 2.03-2.62, P < 0.001), surgical intervention 2.21 (95 % CI, 1.22-4.01, P = 0.009), pre-injury health conditions including pre-injury comorbidity 1.52 (95 % CI, 1.24-1.86, P = 0.0020), and pre-injury anti-thrombotic therapy 1.51 (95 % CI, 1.23-1.84, P < 0.001) were related to higher in-hospital mortality in elderly patients with TBI. Subgroup analyses according to multiple types of antithrombotic drugs with at least two included studies showed that anticoagulant therapy 1.70 (95 % CI, 1.04-2.76, P = 0.032), Warfarin 2.26 (95 % CI, 2.05-2.51, P < 0.001), DOACs 1.99 (95 % CI, 1.43-2.76, P < 0.001) were related to elevated mortality. Dose-response meta-analysis of age found an odds ratio of 1.029 (95 % CI, 1.024-1.034, P < 0.001) for every 1-year increase in age on in-hospital mortality. Conclusions: In the field of elderly patients with TBI, the overall in-hospital mortality and its temporal-spatial feature, the subgroup in-hospital mortalities according to injury severity, and dose-response meta-analysis of age were firstly comprehensively summarized. Substantial key risk factors, including the ones previously not elucidated, were identified. Our study is thus of help in underlining the importance of treating elderly TBI, providing useful information for healthcare providers, and initiating future management guidelines. This work underscores the necessity of integrating elderly TBI treatment and management into broader health strategies to address the challenges posed by the aging global population.